rich on decel
Thread Starter
Staging Lane
Joined: May 2017
Posts: 66
Likes: 0
rich on decel back for more abuse...so i got the truck back together and running well, the truck will idle a 14 afr and is good cruising around the same out of boost but if i crack it and come out of boost im running like 10 to 11 afr then comes back to 14 after i get back into the throttle back to cruise. i feel as though if im out f boost ther is really no reason to be rich and would like to try to get stock economy or at least close when not in boost
blue ve chnge.hpt
blue ve chnge.hpt
What injectors are in the vehicle? Being rich on decel is actually pretty common. This is one of the reasons that GM and other companies implement a DFCO strategy. That and fuel mileage of course. The issue with decel, is that the engine is under extremely high vaccuum (I.E. Very low absolute pressure), thus there is very very little air in the cylinders. To achieve the amount of fuel for this extremely low amount of air, the injector is usually commanded an IPW that is below it's minimum pulsewidth. So, it defaults to the minimum pulsewidth, and thus runs rich. This phenomena is even worse the bigger the injectors you run.
Does this make sense?
Does this make sense?
Thread Starter
Staging Lane
Joined: May 2017
Posts: 66
Likes: 0
What injectors are in the vehicle? Being rich on decel is actually pretty common. This is one of the reasons that GM and other companies implement a DFCO strategy. That and fuel mileage of course. The issue with decel, is that the engine is under extremely high vaccuum (I.E. Very low absolute pressure), thus there is very very little air in the cylinders. To achieve the amount of fuel for this extremely low amount of air, the injector is usually commanded an IPW that is below it's minimum pulsewidth. So, it defaults to the minimum pulsewidth, and thus runs rich. This phenomena is even worse the bigger the injectors you run.
Does this make sense?
Does this make sense?
^^ yea that is what I would do. Or change up the settings for the DFCO. Usually the stock settings are pretty good. Usually u turn off DFCO when tuning fuel trims. Check and make sure its not off.
Thread Starter
Staging Lane
Joined: May 2017
Posts: 66
Likes: 0
I can pull all the fuel out of those sections and it is still rich on decel so I have them where there at so it doesn't idle over a 15 afr. I did all I could with the ve in those spots to try to straighten it out before I came to you guys
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You are currently at .005 in your tune so that's not your issue. Welcome to larger injectors and riding the minimum pulsewidth, even good injectors such as the ID 850s aren't immune to things like this when your motor just plain doesn't need that much fuel. Either get DFCO to come on more aggressively and cut all fuel on decel or just deal with it because once you ride the minimum pulsewidth of an injector you aren't going to be able to lean it out anymore.
Thread Starter
Staging Lane
Joined: May 2017
Posts: 66
Likes: 0
You are currently at .005 in your tune so that's not your issue. Welcome to larger injectors and riding the minimum pulsewidth, even good injectors such as the ID 850s aren't immune to things like this when your motor just plain doesn't need that much fuel. Either get DFCO to come on more aggressively and cut all fuel on decel or just deal with it because once you ride the minimum pulsewidth of an injector you aren't going to be able to lean it out anymore.
Not like VE. You have qualifiers that allow it to go into DFCO like MAP sensor readings, RPM, etc. I have no idea what your combo is but more than likely you will have to adjust MAP entry/exit and engine RPM allowed.